In Polish there's an expression Słomiany zapał which is a play on words, Straw enthusiasm and Straw going ablaze.
The idea is that straw burns with a very bright flame but the fire dies out very quickly. The fire is not sustaining and produces little heat in the long run. Following this metaphor, the expression describes a significant (and very common) vice of engaging in new projects with outstanding enthusiasm only to lose interest in them before they reach their fruition.
Is there any counterpart to this expression in English?